Lateral Intracerebroventricular Injection Of Apelin-13 Inhibits Apoptosis After Cerebral Ischemia/Reperfusion Injury

BackgroundIschemic stroke is the most common disorder of clinical cerebrovascular diseases and it is well accepted that early thrombolysis is the most effective method to treat it at present. Since reperfusion injury will be inevitably happened to ischemic brain tissue is attracting more and more neurologists and researchers pay their attention on its pathogenesis. Apoptosis is one of the main pathogenesis of cerebral ischemia/ reperfusion (I/R) injury, which plays the key role in the lesion. Therefore, interfering any step of cell apoptosis would shed light on treatment of ischemic stroke. Apelin-13 is a endogenous ligand of G protein coupled receptor APJ. Some studies have shown that Apelin-13 can inhibit the cerebral I/R inflammatory reaction and alleviate cerebral I/R injury and cerebral edema in rats I/R models. Whether Apelin-13 can play neuroprotective role through inhibiting the apoptosis of neurons and its possible mechanism need further study.ObjectivesTo investigate the neuroprotective effect of lateral intracerebroventricular injection of Apelin-13 on cerebral I/R injury in Wistar rats and the inhibition mechanism of neuron apoptosis, expect to provide more experimental evidences for the treatment of ischemic stroke.MethodsHealthy adult male Wistar rats were randomly divided into the control group, cerebral I/R group and Apelin-13 treatment group. The cerebral I/R injury model were made by the method of middle cerebral artery occlusion(MCAO) to the rats in cerebral I/R group and Apelin-13 treatment group with ischemia for 1 or 2 hours and reperfusion for 24 hours after restricing food and water intake for 12 hours. Apelin-13 was injected into the rats’ lateral ventricles in Apelin-13 treatment group after reperfusion. Neural function defect score was made to the rats after reperfusion 24 hour. The volume of infarction was evaluated by 2,3,5-triphenyltetrazoliumchloride (TTC) staining. The number of apoptosis neurons in the brain tissue of ischemic penumbra was detected by TdT-mediated dUTP nick-end labeling (TUNEL) staining. The levels of B cell lymphoma/leukemia 2 (Bcl-2) and cysteinyl aspartate-specific proteinase-3 (Caspase-3) in the brain tissue of ischemic penumbra were detected by immunohistochemistry (IHC). The expression level of yes-associated protein (YAP) in the cerebral cortex, hippocampus and thalamus were detected by Western blot technology.Results1.The results of behavioral score show that the method Apelin-13 injected into the rats’lateral ventricles can Improve the neurological defect symptoms which caused by cerebral I/R injury with ischemia for 1 hour and reperfusion for 24 hours to the rats.2. The results of TTC staining show that the method Apelin-13 injected into the rats’lateral ventricles can significantly reduce the cerebral infarction volume of rats with ischemia for 1 hour and reperfusion for 24 hours.3. The results of TUNEL staining show that the method Apelin-13 injected into the rats’lateral ventricles can reduce the number of apoptosis neurons in the brain tissue of ischemic penumbra of rats with ischemia for 1 hour and reperfusion for 24 hours.4. The results of IHC staining show that the method Apelin-13 injected into the rats’lateral ventricles can increase the expression level of Bcl-2 while decrease the expression level of Caspase-3 of rats with ischemia for 2 hours and reperfusion for 24 hours.5. The results of Western blot show that the expression level of YAP in the cortex, hippocampus and thalamus of rats with ischemia for 1 hour and reperfusion for 24 hours was more than the control rats. In every part of the rats brain tissue, the expression level of YAP was increased after injected Apelin-13 into the rats’lateral ventricles.ConclusionsInjected Apelin-13 into the rats’ lateral ventricles can inhibit the rats neuron apoptosis after acute cerebral I/R injury; The neuroprotective effect of Apelin-13 may be related to upregulation of anti apoptotic factors and inhibit the expression of Pro-apoptotic factors; The Hippo signal transduction pathway is involved in cerebral I/R injury and the neuroprotective effects of Apelin-13 in rats.